OK this may seem a very dumb question as I am an engineer and have been working on cars for over 40 years but only at age 60 got my first "motor bike type thing", a polaris ATV

it says 425 cc four cycle and it has valves etc - now my understanding was 2 stroke is like a motor mower where you MIX oil in the fuel in a can and pour the mix in - the oil lubricates [and smokes]

but in a car you dont mix any oil of course as you have a separate oil circ system

now in my ATV I still need to put in oil which somehow gets injected to fuel side and makes smoke

so if it is 4 stroke/cycle and has all the goodies of a car [ie sump and oil pump etc] then why do I need to put separate oil in

 

Thats because it is a 2 stroke. If in deed it is a 94 they made a 400, 350 and 300. All 2 strokes. They did not come out with 4 stroke till 96.

 

Little confused on the question but here you go. [img]i/expressions/face-icon-small-happy.gif[/img]

If the quad is a 4 stroke you do not need to mix oil and gas. Depending on the quad it may or may not have a oil tank and then it will also have a spot to fill into the crankcase. Depending on the quad many run what is called a wet clutch so the oil not only lubes the motor but it also lubes the clutch. So if there are 2 spots to put oil, they are part of the same lube sytem it is just getting oil to both halfs before you start it up versus putting it all in the oil tank and the rest starting dry.

If it is a 2 stroke then you have to mix oil and gas.

Hope that helped a little anyway lol [img]i/expressions/face-icon-small-happy.gif[/img]

 

Another thing to add, the polaris 4 strokes have a oil tank because they are a dry sump engine. Instead of the oil being in the bottom of the crankcase and being distributed from there, the engine has very little oil stored in it. The oil is pumped through the engine then cycled back out to the oil tank.

 

OK I think you have confirmed what I suspected ie that this 4 stroke design is a hybrid, ie it has valves etc ie IS a 4 stroke but has a dry sump so relies on injection of oil

other thing is it only smokes until it is warmed up so maybe the oil is as you say mainly for engine lube [and clutch] but also injects in to fuel at the critical wear part when you start up

 

doc,

I watched your videos and if your bike is the one in the video, then it has a 2-stroke engine. There is no such thing as a 4-stroke hybrid with valves and oil injection for the critical wear parts. It's one or the other. There was only one 6-stroke engine designed but it never made production. Your engine is a 2-stroke and you either mix oil with the gas or you just fill an oil injection tank.

 

OK, so you are confirming that from the SOUND of the engine?

for sure I thought it sounds a bit "put put" but I wouldnt really know

thanks for the reply - I guess I would rather NOT ever have to find out by having to take the head off for maintenance so I will just stop wondering about all this, because for sure I have far more impt issues at hand

 

That AND the tell-tale shape of a two-stroke exhaust expansion chamber that I can see on the right side of your bike.

 

Your quad is a 400cc two-stroke, i can see the 400 stickers on the pics. from 2004. it is not a 4-stroke 425.

 

Plus, it has the tell-tale oil filler on the nose. Definitely a smoker.